Question

Similar cells are used to light similar bulbs in the circuits.
Which lamp is brightest and which is dimmest ?

• A. Brightest -Q Dimmest - P
• B. Brightest - Q Dimmest - R
• C. Brightest - R Dimmest - P
• D. Brightest - R Dimmest - Q

Answer 1

The correct option is B Brightest - Q Dimmest - R

power in (i) = $\frac{V^2}{R}$
power in (ii) = $\frac{(2V{)}^2}{R}$ = $\frac{4(V{)}^2}{R}$
power in (iii) = $\frac{(V-\frac{V}{2}{)}^2}{R}$ = $\frac{1}{4}\frac{(V{)}^2}{R}$
we can see that power in (ii) > (i) > (iii)